A suicide bomber blew himself up during the funeral service of an anti-Taliban tribal elder in northwest Pakistan Thursday, killing 31 people and wounding at least 63 others.

The attack took place in the town of Jandol in the Lower Dir tribal area, as more than 100 people gathered in an open field for the ceremony.

No one has claimed responsibility for the attack, but the Pakistani Taliban has stepped up attacks on pro-government tribes.

Also Thursday, U.S. officials said a CIA drone strike killed al-Qaida's chief of operations in Pakistan, Abu Hafs al-Shahri. They said Shahri was killed earlier this week, but did not give details.

Pakistani security officials said a U.S. drone strike killed at least three people in the North Waziristan tribal region Sunday. It was unclear whether that attack was the one which killed Shahri who, according to U.S. officials, worked closely with the Pakistani Taliban to carry out attacks inside Pakistan.

Shahri was also considered a possible replacement for al-Qaida's deputy leader, Atiyah Abd al-Rahman, who was killed in a U.S. drone strike in Pakistan's northwest tribal region on August 22.

U.S. special forces killed the terror network's leader, Osama bin Laden, during a covert raid in the Pakistani city of Abbottabad on May 2.

Earlier this month, Pakistan's military said security forces had arrested senior al-Qaida leader, Younis al-Mauritani, and two other al-Qaida operatives during an operation in the southern port city of Karachi.

Bin Laden reportedly tasked Mauritani with targeting economic interests in the United States, Europe and Australia.

The White House praised the arrest of Mauritani as an example of the longstanding partnership between the U.S. and Pakistan in fighting terrorism.